Method for the preparation of poly-epoxy condensates

ABSTRACT

EPOXY RESINS HAVING A MAXIMUM SOFTENING POINT ABOVE 95-97*C. ARE PREPARED BY CONDENSATION OF B-METHYL EPICHLOROHYDRIN OR B-CHLOROMETHYL EPICHLOROHYDRIN WITH BISPHENOL-A IN A SINGLE REACTION STEP IN THE ABSENCE OF A SOLVENT OTHER THAN DIOXANE.

United States Patent 3,553,165 METHOD FOR THE PREPARATION OF POLY-EPOXY CONDENSATES Tomoo Kiryfi, Zushi-shi, Japan, assignor to 'Chiyoda Kako Kensetsu Kabushiki Kaisha, Tokyo, Japan, a corporation of Japan Filed Apr. 28, 1966, Ser. No. 546,055 Int. Cl. C08g 30/04 US. Cl. 260-47 7 Claims ABSTRACT OF THE DISCLOSURE Epoxy resins having a maximum softening point above 95-97 C. are prepared by condensation of fi-methyl epichlorohydrin or B-chloromethyl epichlorohydrin with bisphenol-A in a single reaction step in the absence of a solvent other than dioxane.

This invention relates to a method of manufacturing novel epoxy resin condensates.

More specifically, this invention relates to the manufacture of entirely novel epoxy resin condensates having high softening point through a single reaction step, that is, by condensation of B-methyl epichlorohydrine (1H3 (H2C 0-oH Cl) or B-chloromethyl epichlorohydrine (Inner (H2C CCH2C1) o with 2,2-bis-(p-hydroxyphenyl)-propane (Bisphenol-A), in the absence of solvent or in the presence of dioxane. These compounds may be represented by the formula:

wherein X is hydrogen or chlorine.

It has been known in the art that high-molecular compounds are formed by condensation of polyhydric phenols with epichlorohydrines in the presence of alkaline solutions.

According to the known processes, the epoxy resin condensates which can be prepared by a single reaction step have maximum softening points of only 95 to 97 C. This may be attributed to the following presumption, for example in the reaction of epichlorohydrine with Bisphenol-A:

that is to say, when a reaction is elfected by the addition of 0 mol of caustic soda to :1 mol of epichlorohydrine and b mol of Bisphenol-A, a resin condensate corresponding to the first item on the right side of Formula 1 is made, accompanied by the formation of d mol of sodium chloride, and the reaction of Formula 1 is terminated.

By the conventional methods of manufacturing epoxy resin condensates, the above product of a single-step reaction has an n value of at most 2, which has chiefly been responsible for the low softening points of the condensates.

Therefore, to obtain resin condensates having higher softening points than the above mentioned maximum ice values, it is only necessary to eliminate any unrequired substance from the reaction system and permit further progress of the reaction rightwardly on the formula. This follows from the Le Chatelier-Brown Principle.

For example, in the reaction of Formula 1, the degree of condensation or the n value of the epoxy resin can be increased beyond 2 by taking out the NaCl of the second term on the right side, from the reaction system.

There are several known operations. According to Reynolds patented invention (Japanese patent publication No. 4,494/1953), an epoxy resin condensate is first prepared by the reaction of an excessive amount of epichlorohydrine with Bisphenol-A, the resin is washed with warm water to remove NaCl from the reaction system, and then a reaction is carried out again by the addition of Bisphenol-A and NaOH to the reaction system thereby to increase the n value beyond 2.

In brief, a high softening-point substance is obtained by two reaction steps.

In Japanese patent publication No. 1,548/ 1957, also by Reynolds, there is described another procedure for removing NaCl from the reaction mixture.

The method consists of obtaining resin condensates having high softening points, or in which n 2, through a single reaction step with the use of water and water-insoluble solvent mixed beforehand in the reaction system. While the reaction proceeds in the solvent, NaCl formed by the reaction is transferred from the solvent to water. In other words, NaCl is extracted with water and the reaction is allowed to proceed rightwardly of the formula given hereabove.

In short, the products of conventional reaction steps have softening points of at most to 97 C., and, in order to permit further progress of the condensation, it is essential to remove NaCl from the reaction system. For this reason, either a resin product is prepared first and NaCl is removed from the production system and then the above reaction is repeated thereby to obtain a substance of a high softening point, or the reaction is effected in a solvent which is insoluble in water and the NaCl secondarily produced is transferred into water and then the reaction is allowed to proceed thereby to obtain a resin condensate of a high softening point.

The present invention concerns a method whereby the difliculties involved in the complicated and troublesome process of conventional methods are overcome, and epoxy resin condensates having high softening points as compared with the products of ordinary methods are obtained by a novel, single-step operation. More particularly, the present invention concerns a method of obtaining resin condensates of high softening points by a single-step operation to make n 2.

The present invention provides a method of manufacturing epoxy resin condensates by the use of 3-methyl epichlorohydrin or 3 chloromethyl epichlorohydrin in lieu of epichlorohydrine which have hitherto been in common use for this purpose. There is no precedent of the use of any such compound in the manufacture of epoxide resin condensates. It is expected, however, that these materials will become available in large amounts in the future, with the development of petrochemical industry. For example, bulk production of such a compound is readily made possible by chlorination of isoit attained a temperatureof 60 C. in about 20 'rniirbutene contained in the butane-butylene fraction. utes. Above Bisphenol-A usually melts at about 57 to Now a typical example of the invention using B-methyl 60 C. To the solution, different proportions of epichloroepichlorohydrine '(1,2 epoxy 2 methyl-3-chloroprohydrine were added. pane), 'is illustrated by the following chemical formula. 5 Since the reaction was exothermic, the reaction teml i t 0 CH3" H a v em I" e a "I our" our H2oo-on2-0-o-C -oorn+o-oH20-C o -0-orn-oom a. NaOl I l l o 0H3 0H s CH3 0 2) The softening point of the resin condensate thus obperature would rise to about90" C. Under the suitable tained is remarkably high as compared with those of controls, the temperature. was kept within the. range of the" resin condensates made by the use of epi'chlorohy- 15 about 75 to'80" C. In a few minutes, the mixture was d i whitened, but was continuously heated in thesame tem- "In contrast to the cumbersome methods heretofore in perature range for one hour. The reaction mixture use for enhancing the degrees of polymerization, the gradually turned transparent and. became-homogeneous. method provided'by the present invention enables epoxy Then, the "total reaction product was' washed with the resin condensates having high degrees of polymerization, same amount by weight of'water for 15 to -20 minutes. or high softening points, to be obtained without any This was repeated five to seven times until the washings forcible desalting operation but by mere washing of the attained a pH value of about 7. reactant with water on completion of the reaction. Further, the resin thus Obtained Was heated, dried With As described above, the present invention makes use of Stirring, and completely dehydrated with a temperature fi-chloromethyl epichlorohydrin instead of epichlorohyrise up to 170 C. The Soft Points Of the resin drine generally in use. Therefore, practically all the reac- Condensate specimens thus obtained are indicated by full tion conditions employed in the conventional methods lines in FIGS. 1 and 2. The differences between the for the manufacture of epoxy resins from epichlorohydotted lines and full lines were approximately 15 to drine are applicable to the method of the present inven- 25 C. This means that the resins produced in accordtion. ance with the invention have softening points which are An exception is the use of dioxane as the solvent. It always higher by 1 5 to 25 C. than those of the condissolves high-softening point resins formed and lowventional products obtained under similar reactive coners the reaction temperature of the present invention, ditions. and brings a desirable effect of extremely lowering the While ,B-methyl epichlorohydrine was adopted in the viscosity of reaction mixture, thereby facilitating the above example, it may be substituted by fl-chloromethyl stirring operation. The amount of dioxane to be used is epichlorohydrine to raise the softening point by about approximately equal by weight to the total amount of 30 to more than about 40 C., and the use of dioxane reaction materials. Thus, the present invention covers the as a solvent vehicle causes a drop in the reaction temuse of dioxane as the solvent. perature. These are illustrated by the following examples.

Of course, it is claimed that the use of dioxane is 40 covered by the invention even when the solvent is not EXAMPLE 2 specifically employed. To a mixture consisting of one mol of ,B-methyl-epi- The resins obtained by the practice of the present inchlorohydrin, 2 mols of Bisphenol-A and 4 mols of divention are characterized by a far greater resistance to oxane as the solvent, 3 mols of an aqueous solution oils than the conventional epoxy resins. containing 10 wt. percent NaOH were added. The whole For a better understanding thereof, the present invenmixture was reacted under 2 atm. and at 100. C. The tion is illustrated by the following examples, which are epoxy resin thus obtained, on washing with water and in no way restrictive. drying, had a softening point of 112 C. and an epoxy a equivalent of"580'. (When the solvent was not em loyed, EXAMPLE 1 v 0 the reaction temperature rose to about '120 C.) l y con- Into an autoclave having acap'acityof one liter, 4 trast, an epoxy resin produced by a single-step reaction mols of Bisphenol-A were introduced. 4 H of the epichlorohydrin and Bisphenol-A of the same molar Various parts of a 11.6 wt. percent NaOH solution and ratio as above in the absence of the solvent had a soften- B-methyl epichlorohydrine were added, and each mixture ing point as low as 93; C. was stirred while being heated for 20' to 30' minutes. i

Stirring was carried-out slowly at first and then vigor- EXAMPLE 3 ously by degrees after the start of condensationfThe T0 6 miXtule Consisting of one Ihel of fi' y p reaction temperature rose gradually from 100 C. up chlorohydrhl, 3/1 11101 of BiSPheIIOI-A, and H1013 of to. 170 C. and the pressure reached 4 at Af h dioxane as the solvent, one mol of NaOH was added in reaction for about 30 minutes, the autoclave was opened, the form of a W p r en aqueous Solution. The a d th a tio product was h d i h h same whole mixture was reacted under 5.2 atm. and at 120 C. amount by weight of water, at 170 C. and under an in- 1 The P Y resin which resulted had a Softening Point creased pressure of 10 atm. for 2 0 minutes. The washof (When the Solvent Was not p ye in the ing was repeated five or sixtimes, and stopped when th reaction, the reaction temperature increased to about wash ngs attained a PH value of about 7. I 170- C- i The softening points of the test specimens of resin However, as described in Example 2, the P Y resin condensates thus obtained (as determined in accordance Produced from epichlorohydrine" and BiSPheHOI-A 0f the with the rosin ring-ball method, 118 K5902) are indi- Same molar ratio, but in the absence of the solvent, had cated by dotted lines in FIGS..1 and 2. r a softening point of 95 JC. at most.

Besides the above, epoxy resin specimens of a commonlyxknown type were prepared in the following way. EXAMPLE 4 Into a three-necked flask equipped-with a cooler, a To 'a mixture of one mol of epoxide of ,B-chlor'othermometer, and a stirrer, 4 mols of Bisphenol-A and methylepichlorohydrin and '3 mols of Bisphenol-A, 2 various parts of a 11.6 wt. percent NaOH solution were mols of NaOH in the form of a 10 wt. percent aqueous introduced. Each mixture was heated at such a rate that solution were added, and the whole mixture was reacted at 170 C. and under 5.1 atm. The epoxy resin thus obtained, on washing with water and drying, had a softening point of 160 C. and an epoxy equivalent of 720. When dioxane was used as the solvent in this reaction, a reaction temperature of 120 C. was suflicient for the purpose. The softening point of the epoxy resin obtained by a single-step reaction of epichlorohydrine and Bisphenol-A of the same molar ratio as above but in the absence of the solvent was not beyond 98 C.

I claim:

1. Process for preparing an epoxy resin having a softening point above about 97 C. and having the formula CHzX CHzX

3. Process according to claim 1 wherein said epoxy compound is B-methyl epichlorohydrin.

4. Process according to claim 1 wherein said epoxy compound is fi-chloromethyl epichlorohydrin.

5. Process according to claim 1 wherein the mole ratio of said epoxy compound to said 2,2-bis-(p-hydroxyphenyl)-propane is in the range of about 3.6:4 to about 9:4.

6. Process according to claim 3 wherein the mole ratio of NaOH to said epoxy compound is in the range of about 1:1 to about 3:1, the mole ratio of said epoxy compound to said 2,2-bis-(p-hydroxyphenyl)-propane is in the range of about 2:4 to about 5 /3 :4, and the amount I OH wherein n is 2 to 3 and X is hydrogen or chlorine, which process comprises (I) reacting in a single reaction step an epoxy compound of the formula of dioxane in said water-dioxane mixture is approximately equal by weight to the total amount of said epoxy compound and said 2,2 bis-(p-hydroxyphenyl)-propane.

7. Process according to claim 6 wherein the mole ratio of NaOH to said epoxy compound is about 2:1 and the mole ratio of said epoxy compound to said 2,2-bis-(phydroxyphenyl)-propane is about 4/3 :4.

References Cited UNITED STATES PATENTS 3,277,051 10/1966 Wynstra 260-47EP 2,866,057 12/1958 Peck 26047 EPCN 3,305,528 2/1967 Wynstra et al. 260-47EP OTHER REFERENCES Lee et al.: Epoxy Resins, p. 15 relied on, McGraw- Hill Book Co., Inc. New York, 1957.

WILLIAM H. SHORT, Primary Examiner T. E. PERTILLA, Assistant Examiner 

